mordey



No. 615,71. Patented Dec. l3, I898.

, W. M. MURDEY.

DYNAMO ELECTRIC MACHINE.

' (Application filed Feb. 15, 1897.) (No Model.) 3 Sheets-Sheet I.

No. 6l5,73l. Patented Dec. l3, I898. W. M. MORDEY.

DYNAMO ELECTRIC MACHINE.

3 Sheets-Sheet 2.

(No Model.)

No. 615,73l. Patented Dec. l3, I898. W. M. MORDEY.

DYNAMO ELECTRIC MACHINE.

- (Application filed Feb. 15, 1897.)

(No Model.) 3 Sheets-8heet 3.

Wm} I g I UNITED STATES PATENT DEEICE.

\VILLIAIWI MORRIS MORDEY, OF LOUGHBOROUGH, ENGLAND.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 615,731, dated December13, 1898.

Application filed February 15, 1897. Serial No. 623,451. (No model.)

To all whom it may concern.-

Be it known that I, WILLIAM MORRIS MOR- DEY, a subject of the Queen ofGreat Britain and Ireland, residing at Loughborough, in the county ofLeicester, England, have invented Improvements in Dynamo-ElectricMachines, (for which I have obtained foreign patents as follows: inGreat Britain, dated June 17, 1896, No. 13,405; in France, datedDecember 16, 1896, No. 262,256; in Italy, dated December 31, 1896, Reg.Att., Vol. LXXXV, No. 107; in Belgium, dated December 17, 1896, No.125,233; inAustria, dated March 18, 1897, No. 47/927; in Germany, datedJanuary 17, 1897, No. 99,019; in Switzerland, dated January 16, 1897,No. 13,928; 'in Norway, dated March 5, 1897, No. 6,578; in Canada, datedJuly 23, 1897, No. 56,759, and in Hungary, dated April 12, 1897, No.9,278,) of which the following is a specification.

This invention has for its object improvements in dynamos, and relatesparticularly to the removal in a simple and inexpensive way of thedifficulties caused by sparking and armature reaction, whichdifficulties are most pronounced in machines having armaturewindingssunk in slots or holes in the ar1nature-core, especially when armaturesso constructed are used with a small clearance or air-space between thearmature and the poles of the field-magnet. In such machines thearmature reaction is considerable and the output is greatly reduced bythe sparking at the brushes and the necessity for a large forward lead.

The following is'a description of a Gramme dynamo constructed accordingto my invention. The armature is preferably made with slots or holes atthe outer surface. The coils are wound in the usual way, the number ofturns for any given electromotive force being substantially the same asin the ordinary armature; but instead of connecting the consecutivecoilsin series (as is usual in a Gramme winding) each coil is joined toanother coil situated a certain distance away on the armature-core,these two coils so separated being treated as a single coil so far asconnection to the commutator is concerned, as I shall now proceed toexplain by reference to the accompanying drawings, wherein- Figure 1shows, diagrammatically, in end elevation part of a Gramme dynamo witharmature-coils arranged according to my invention. Fig. 2 is a developedplan view showing, diagrammatically, a greater portion of thearmature-winding than Fig. 1. Figs. 3 to 7, inclusive, show variouspositions of one ele ment of the winding. Fig. 8 is a diagram showingpart of a dynamo according to this invention with an auxiliary pole.

Referring to Fig. 1, 1 is the armature-core, formed at its outer surfaceor periphery with slots2, in each of which and around the core are woundtwo armature-coils 3 3. For the sake of clearness I indicate only sixcoils. At A there are two coils 3 3. At 13 come the next two coils 3 3.At G are other two coils 3 3. It is to be noted that the distancebetween the coil 3 at A and the coil 3 at G is, according tomyinvention, equal or approximately equal to the distance or gap Dbetween the tips of the adjacent poles N S. The parts being thusarranged, the connections of the coils are as follows: One end of thecoil 3, located at A, is in communication with one segment (or sector)4.- of the commutator. The other end of the same coil 3 is connected toone end of the coil 3, located at G. The other end of thislast-mentioned coil 3 is connected by a conductor 3 to that end of thecoil 3 located at B, which communicates with the commutator-segment a.All the coils of the armature are to be connected according to themethod just above explained. Each connected pair of coils 3 3constitutes one element of the whole winding. It will be seen that withthis connection of the coils the cur rent and electromotive force are inthe same direction in each connected pair of coils or element during thegreater part of each halfrevolution, but that as the element comes intothe region of commutation its two connected parts have generated in themopposing electromotive forces, due to the fact that while one part isunder the tip or end of one polepiece the other part is under the tip orend of the next following polepiece of opposite polarity. In this way Iam enabled to collect in an active part of the field without sparkingand with a smaller forward lead of the brushes than is usual, or with nolead of the brushes,or even with abackward lead thereof, therebyenabling me to obtain the economy of power and of material that resultfrom the use of a small air-gap. The actual collecting position isdetermined by the relation as to number of turns or of angular position,or both, of the connected portion of each element.

Fig. 2 is a developed plan view showing,

diagrammatically, a greater number of elements than Fig. l and alsoillustrating the relation of the elements to each other, to thefield-magnet poles N S, (shown in dotted lines,) to the interpolar gap,and to the commutatorsegments, some of which are shown at 4 4c 4 4i.Figs. 3, 4, 5,6, and 7 show five successive positions of one element ofthe winding. In these diagrammatic views the slots shown at 2 in Fig. 1are omitted in order to simplify the drawings. The small arrows indicatehow the electrom otive forces in the two coils constituting this oneelement assist one another in the positions represented in Figs. 3 and7that is to say, during the greater part of the revolutionand how in theposition represented in Fig. 5 the said forces 01)- pose one another.The act of commutation should occur just when or a very slight intervalof time after the position represented in Fig. 5 is attained. Figs. atand 6 show two intermediate positions of the element.

By way of further elucidation I will now compare an example of myarrangement with an ordinary Gramme arrangement having the same numberof turns or convolutions. I select for this comparison an ordinaryGramme ring in which there are four hundred and twenty turns orconvolutions grouped as sev enty successive elements of six turns orconvolutions each, furnished with a commutator having seventy segmentsor bars, the beginning of each element of the winding being connected toone segment of the commutator and the end of such element beingconnected to the next adjacent segment of the commutator. Now accordingto my invention this same Gramme ring would be modified in itsdisposition, as follows: Each element of six convolutions would beseparated into two coils, each of three convolutions. The second of thecoils would be wound on the ring at a certain distance from the first,(along the ring,) as hereinbefore fully described; but the whole sixconvolutions would still be joined in series between two adjacentsegments of the commutator. There would still be seventy segments in thecommutator and four hundred and twenty convolutions, in total, aroundthe ring.

I may use a larger or smaller number of slots in proportion to the coilsthan are shown in the drawings and referred to in the foregoingdescription. For example, I may have only one turn in each slot orI mayhave several turns, or, on the other hand, I may distribute the portionsof each element over several slots without departing from the spirit ofmy invention.

Auxiliary poles may be used between the ordinary pole-tips, so arrangedas regards position and polarity as to produce in one coil or portion ofeach element passing through the region between the pole-tips anelectromotive force similar to that produced by one of the poles. Thepolarity to be given to each auxiliary pole for a Gramme armature shouldbe the reverse of that for a drum armature. Fig. 8 is a diagrammaticillustration of such an arrangement as applied in a machine of Grammetype. N S are the ordinary poles, and A is an auxiliary pole placedbetween the tips of the two poles N S. In such an arrangement the gap d,together with the relative number of turns in the portions 3 and 3 ofeach element, determines the distance apart of the coils 3 8 of eachelement. The auxiliary pole A in this case should have S polarity and inthe next succeeding space the auxiliary pole should have N polarity,assuming that commutation takes place approximately in the positionshown in Fig. 8 and with a right-handed direction of rotation of thearmature. In a drum dynamo A should have the reverse polarity to thatfor a Gramme because the separate portions of the element should beunder the influence of similar polarities at the time of commutation. Itis to be understood that Fig. 8 shows only the auxiliary pole betweenone pair of poletips, the space or spaces between the other pole-tipsbeing provided with auxiliary poles having the same order as regardspolarity. The auxiliary poles are conveniently magnetized by a windingin connection with the ordinary field-winding, preferably by ashuntwinding, to give an initial magnetization and by a series windingto increase or maintain the magnetization as the load increases, afterthe manner of a compound-wound field magnet.

In applying my invention in lnultipolar machines, whether with series orparallel winding, I space the winding so that the electromotive forcesin any one element of the winding oppose one another during the momentof commutation but aid one another during the greater part of therevolution.

My improvements are applicable to dyna mos whether used as generators oras motors. Also, although I have described my invention by way ofexample mainly in connection with a dynamo having an armature of theGramme type, it is of course equally applicable to dy namos havingarmatures of the drum type, as described in the specification of anotherapplication for Letters Patent, Serial No. 664,767, filed by me as adivision of this ap plication.

I know that a method of couplinghas been proposed according to which atthe time of commutation a coil under the influence of a field-magnet isin series with one not then un-- ICC der that influence. In such anarrangement the current flows in different ways in the coils, the objectarrived at being to lessen the crossmagnetizing effect. Such aconnection or coupling, however, is different from mine and does notgive the same result.

What I claim is 1. Ina dynamo-electric machine, an armature having eachelement of its winding arranged as a pair of coils or separate portionsso disposed and connected that during the greater part of the revolutionthe electromotive forces in the two coils or the separate portions areadditive, while at the time of commutation they are in opposition.

2. In a dynamo-electric machine a Gram me armature having twice as manycoils as there are segments of the commutator, the said coils beingjoined two in series so as to form pairs of coils each of which pairsconstitutes one element of the winding, the angular breadth or spacingbetween the two coils constituting each element being equal orapproximately equal to the angular breadth or spacing between the edgesof two adjacent magnetic poles of opposite polarity so that while onecoil is under the tip or end of one pole-piece the other part is underthe tip or end of the next following pole-piece of opposite polarity.

3. In a dynamo-electric machine a Gramme armature having each element ofits winding comprised between two segments of the commutator dividedinto two connected portions which are spaced apart so that at the momentof commutation the two portions will be under the influences of oppositemagnetic fields so that the electromotive forces generated in them willbe in opposition.

4. A Gramme armature having its coils con nected upin pairs each pairbeing connected with a commutator-strip and in series with the otherpairs of coils, one coil of each pair being arranged in advance of andseparated from the other by the rearward coils of other pairs of coils,substantially as described.

5. An armature comprising an annular iron core having longitudinal slotsor recesses in its periphery, a commutator, and a Gramme winding woundin said slots or recesses and composed of coils connected up in pairsforming elements each of which is connected to a segment of saidcommutator, and is arranged in series with the other elements, the coilsof each pair being separated from each other by coils of other elements.

6. A dynamo-electric machine comprising a field-magnet having poles N Sand an armature having an annular iron core 1 formed with longitudinalslots or recesses 2 in its periphery, commutator-segments, and a Grammewinding consisting of a number of pairs of coils 3, 3 located in saidslots or recesses and arranged at a distance apart such that while onecoil is under the tip or end of one pole-piece the other part is underthe tip or end of the next following pole-piece of opposite polarity,one end of each coil 3 being in communication with one segment of thecommutator and the other end of said coil being in connection by aconductor 3 with one end of the corresponding coil 3 to that end of thenext forward coil 3 that is communicated with the next segment of thecommutater, substantially as described and shown.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WILLIAM MORRIS MORDEY.

Witnesses:

PERCY E. MATTOCKS, WM. 0. BROWN.

